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Lattice
Kinds of Lattice Terms modified by Lattice Selected AbstractsFast High-Dimensional Filtering Using the Permutohedral LatticeCOMPUTER GRAPHICS FORUM, Issue 2 2010Andrew Adams Abstract Many useful algorithms for processing images and geometry fall under the general framework of high-dimensional Gaussian filtering. This family of algorithms includes bilateral filtering and non-local means. We propose a new way to perform such filters using the permutohedral lattice, which tessellates high-dimensional space with uniform simplices. Our algorithm is the first implementation of a high-dimensional Gaussian filter that is both linear in input size and polynomial in dimensionality. Furthermore it is parameter-free, apart from the filter size, and achieves a consistently high accuracy relative to ground truth (> 45 dB). We use this to demonstrate a number of interactive-rate applications of filters in as high as eight dimensions. [source] Dicopper(II) Complexes with the Enantiomers of a Bidentate Chiral Reduced Schiff Base: Inclusion of Chlorinated Solvents and Chiral Recognition of1,2-Dichloroethane Rotamers in the Crystal LatticeEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2006Vamsee Krishna Muppidi Abstract Bisphenoxo-bridged dicopper(II) complexes [Cu2Ln2Cl2] {1 (n = 1) and 2 (n = 2)} with the N,O-donor reduced Schiff bases N -(2-hydroxybenzyl)-(R)-,-methylbenzylamine (HL1) and N -(2-hydroxybenzyl)-(S)-,-methylbenzylamine (HL2) have been synthesised and characterised. In both 1 and 2, the bidentate chiral ligands coordinate the metal centres through the secondary amine N atom and the bridging phenolate O atom. The chloride ion occupies the fourth coordination site and completes a slightly distorted square-planar NO2Cl environment around each copper(II) centre. Magnetic susceptibility measurements in the solid state suggest a strong antiferromagnetic interaction between the metal centres in both complexes. Both 1 and 2 readily form 1:1 host-guest compounds with chlorinated solvents such as CH2Cl2, CHCl3 and Cl(CH2)2Cl. All the host-guest compounds crystallise in noncentrosymmetric space groups. 1·CH2Cl2 and 2·CH2Cl2 crystallise in the P21 space group while 1·CHCl3, 2·CHCl3, 1·Cl(CH2)2Cl and 2·Cl(CH2)2Cl crystallise in the P212121 space group. In these inclusion crystals, the C,H···Cl interactions between the guest and the host molecules are primarily responsible for enclatheration of the chloroalkane molecules. In the case of CH2Cl2, one of its Cl atoms acts as the acceptor. On the other hand, for CHCl3 and Cl(CH2)2Cl, the metal coordinated Cl atom of the host complex acts as the acceptor. The structures of 1·(P)-Cl(CH2)2Cl and 2·(M)-Cl(CH2)2Cl provide rare examples for chiral recognition of the right handed (P) and the left handed (M) gauche forms of Cl(CH2)2Cl in molecular assemblies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Time-steppers and ,coarse' control of distributed microscopic processesINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2004Antonios Armaou Abstract We present an equation-free multiscale computational framework for the design of ,coarse' controllers for complex spatially distributed processes described by microscopic/mesoscopic evolution rules. We illustrate this framework by designing discrete-time, coarse linear controllers for a Lattice,Boltzmann (LB) scheme modelling a reaction,diffusion process (a kinetic-theory based realization of the FitzHugh,Nagumo equation dynamics in one spatial dimension). Short ,bursts' of appropriately initialized simulation of the LB model are used to extract the stationary states (stable and unstable) and to estimate the information required to design the coarse controller (e.g. the action of the coarse slow Jacobian of the process). Copyright © 2004 John Wiley & Sons, Ltd. [source] Lattice: Multivariate Data Visualization with R by Deepayan SarkarINTERNATIONAL STATISTICAL REVIEW, Issue 3 2008Klaus Nordhausen No abstract is available for this article. [source] Epitaxial growth of carbon caps on Ni for chiral selectivityPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2006S. Reich Abstract We suggest guiding principles for chirality-selective growth of single-walled carbon nanotubes. The chirality of a tube is determined by the carbon cap that forms during nucleation. Controlling the tube chirality requires controlling the nucleation stage. Certain caps can be favored by their epitaxial relationship to a metal surface. Lattice matched caps require ,0.1 eV/C less formation energy on a Ni surface than non-lattice matched cap structures. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Extending Rectangular Metal,Organic Frameworks to the Third Dimension: Discrete Organometallic Boxes for Reversible Trapping of Halocarbons Occurring with Conservation of the Lattice,ANGEWANDTE CHEMIE, Issue 34 2009Ying-Feng Han "Molekulare Splinte" mit Ir- und Rh-Halbsandwichkomplexen als Eckzentren wurden synthetisiert, charakterisiert und als Halogenkohlenwasserstoff-Fänger getestet. Komplex,1 (M=Ir, Rh) erkennt unter Beibehaltung der Kristallinität selektiv CH2Cl2 - und ClCH2CH2Cl-Moleküle. Diese Komplexe gehen bei Lösungsmittelwechsel reversible Einkristall-Einkristall-Umlagerungen ein. [source] 3334: Corneal dystrophies: the paediatric corneal specialist viewACTA OPHTHALMOLOGICA, Issue 2010KK NISCHAL Purpose To describe the range of corneal dystrophies presenting to a tertiary refferral paediatric ophthalmology centre and the treatment approach to these various dystrophies Methods Retrospective review of case notes between Jan 1999 and March 2010 Results The range of corneal dystrophies presenting varied from Meesmans, Map-Dot , Reis-Buckler, Posterior polymorphous corneal dystrophy, congenital hereditary endothelial dystrophy, Granular and Lattice -Granular and the newly described x linked endothelial corneal dystrophy. The youngest child to present with symptoms was 14 months old. Management approach depended on the ultimate goal of allowing normal visual developemnt until the age of 8 years. Amblyopia plays a great role in the eventual visual outcome in children with corneal transplant surgery also riddled with difficulties in young children. Conclusion The classical descriptions of corneal dystrophies are not how they present in children . Certain symptoms and signs may tip the clinician off to the possibility of a corneal dystrophy. Visual rehabilitation in children is time limited and must be the priority for the treating physician. [source] ChemInform Abstract: On the Correct Spin Lattice for the Spin-Gapped Magnetic Solid NH4CuPO4×H2O.CHEMINFORM, Issue 24 2008Hyun-Joo Koo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Incorporation of an Ionic Conducting Alkali-Metal Halide into a Two-Dimensional Copper Oxide Lattice Through a Novel Stepwise Intercalation Route.CHEMINFORM, Issue 9 2005Dae Hoon Park Abstract For Abstract see ChemInform Abstract in Full Text. [source] Evidence of Ni(III) Disproportionation in the TlNiO3 Perovskite Lattice Through Neutron Powder Diffraction and Moessbauer Spectroscopy.CHEMINFORM, Issue 10 2003S. J. Kim Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: "Inverse" Melting of a Vortex Lattice.CHEMINFORM, Issue 36 2001Nurit Avraham Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Assembly of Two-Dimensional DNA Crystals Carrying N4 -[2-(tert -Butyldisulfanyl)ethyl]cytosine ResiduesHELVETICA CHIMICA ACTA, Issue 8 2009Alejandra Abstract DNA Lattices carrying two cytosine residues bearing the N4 -[(tert -butyldisulfanyl)ethyl] group at the apex of hairpin topological markers are prepared for first time. We show that these residues are important for the deposition of DNA lattices on gold surfaces. [source] Fabrication of Millimeter-Wave Electromagnetic Bandgap Crystals Using Microwave Dielectric PowdersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2009Xuesong Lu Electromagnetic bandgap (EBG) structures active in the 90,110 GHz region widely used by security imaging radar were created using different ceramics by a rapid prototyping method informed by finite difference time domain modeling. This solid free-forming method uses a high volatility solvent-based ceramic paste extruded through fine nozzles allowing ceramic powders to be assembled on a multiaxis building platform avoiding machining, etching, or the alignment of loose rods and created to designs downloaded directly from a computer file. Lattices were made from two high dielectric constant ceramics: La(Mg0.5, Ti0.5)O3 and (Zr0.8, Sn0.2)TiO4 and compared with those of Al2O3 demonstrating three EBG structures with different dimensions and dielectric constants but with the same bandgap. The effects of manufacturing tolerances on bandgap frequency are investigated by simulation. [source] Architecture of Polymeric Superstructures Constructed by Mesoscopically Ordered Cubic LatticesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 4 2003Koji Ishizu Abstract Highly monodisperse crosslinked core-shell polymer microspheres could be prepared easily by introducing special crosslinking reagents into the segregated core in block copolymer assembly films. The crosslinked core was stabilized sterically by highly branched shell chains in solution. These microspheres moved like pseudo-latex. The microspheres formed a lattice with a body-centered cubic (BCC) structure near the overlap threshold (C*). This structure changed to a face-centered cubic (FCC) lattice in the bulk region of the films. Photofunctionalized core-shell microspheres were prepared by introducing dithiocarbamate (DC) groups into shell parts by means of polymer reactions, where DC groups could be propagated using vinyl monomers such as methyl methacrylate (MMA) with living radical mechanism. Polymeric superstructure (three microphase-separated structure) films were constructed by graft copolymerization of MMA initiated with photofunctionalized microspheres such as macroinitiators under UV irradiation, exhibiting self-coloring due to Bragg diffraction. These materials can be used for the construction of optical devices such as for the fabrication of light modulators. Photograph of a solution of the microsphere in MMA. [source] Carrier leakage suppression utilising short-period superlattices in 980 nm InGaAs/GaAs quantum well lasersPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2004D. Lock Abstract Short-period Super Lattices (SSLs) have been proposed as a method of reducing carrier leakage in semiconductor lasers. SSLs increase the carrier confinement by increasing the effective barrier height due to the carriers being "reflected" from the SSL. Thermionically driven leakage of electrons from the quantum wells has been suggested as an important non-radiative current path in (Al)GaAs based devices which is exacerbated at high temperatures. Due to the fact that the application of high pressure causes a reduction in the zone centre ,,X minima splitting, pressure can be used to investigate the extent to which such leakage increase the threshold current. In this study, we compare devices with and without SSL layers and find direct evidence for leakage suppression in devices containing SSLs up to a temperature of 60 °C. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Controllable Polyol Synthesis of Uniform Palladium Icosahedra: Effect of Twinned Structure on Deformation of Crystalline Lattices,ANGEWANDTE CHEMIE, Issue 37 2009Cuncheng Li Einheitliche Pd-Ikosaeder (siehe die TEM-Bilder) wurden in hoher Ausbeute in einem einfachen Polyol-Prozess synthetisiert. Durch Variieren der Reaktionsparameter lässt sich die Partikelgröße zwischen 15 und 42,nm einstellen. Scharfe Oberflächenkanten und eine hohe Dichte an Verzwillingungsgrenzen machen die Nanopartikel zu geeigneten Kandidaten für verschiedene Anwendungen, z.,B. in der Katalyse. [source] Exploring Dependence with Data on Spatial LatticesBIOMETRICS, Issue 3 2009Mark S. Kaiser Summary The application of Markov random field models to problems involving spatial data on lattice systems requires decisions regarding a number of important aspects of model structure. Existing exploratory techniques appropriate for spatial data do not provide direct guidance to an investigator about these decisions. We introduce an exploratory quantity that is directly tied to the structure of Markov random field models based on one-parameter exponential family conditional distributions. This exploratory diagnostic is shown to be a meaningful statistic that can inform decisions involved in modeling spatial structure with statistical dependence terms. In this article, we develop the diagnostic, illustrate its use in guiding modeling decisions with simulated examples, and reexamine a previously published application. [source] ChemInform Abstract: Chemical Tuning of the Photon Upconversion Properties in Ti2+ -Doped Chloride Host Lattices.CHEMINFORM, Issue 52 2001Oliver S. Wenger Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Interactive soft-touch dynamic deformationsCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3 2007Hui Chen Abstract It is crucial for the users to touch, grasp and manipulate the interested objects through our sense of touch in many interactive applications, such as on-line computer games, interactive cartoon design, and virtual prototyping. In this paper, we propose an interactive haptic deformation approach which incorporates the dynamic simulation of mass,spring systems and flexible control of free-form deformation in the touch-enabled soft-object deformation. Through distributing mass, spring and damping coefficients of the object to the bounded Bezier volume lattice, the deformation of the object related to the haptic avatar follows the physical laws and has high working rate. Both homogenous and inhomogenous materials are simulated. The anchor nodes of haptic input are specified to create amazing special effects during the interactive haptic deformation. Interactive haptic deformations of three-type tropic fishes, Angel, Demekin, and GuppyBlueGrass, have been experimented to simulate vivid fish swimming processes in the virtual ocean scene. Our proposed approach provides touch-enabled input and efficient performance in the flexible deforming controls, letting the objects move in a dynamic, cartoon-style deforming manner. Copyright © 2007 John Wiley & Sons, Ltd. [source] Fast High-Dimensional Filtering Using the Permutohedral LatticeCOMPUTER GRAPHICS FORUM, Issue 2 2010Andrew Adams Abstract Many useful algorithms for processing images and geometry fall under the general framework of high-dimensional Gaussian filtering. This family of algorithms includes bilateral filtering and non-local means. We propose a new way to perform such filters using the permutohedral lattice, which tessellates high-dimensional space with uniform simplices. Our algorithm is the first implementation of a high-dimensional Gaussian filter that is both linear in input size and polynomial in dimensionality. Furthermore it is parameter-free, apart from the filter size, and achieves a consistently high accuracy relative to ground truth (> 45 dB). We use this to demonstrate a number of interactive-rate applications of filters in as high as eight dimensions. [source] Transferring the Rig and Animations from a Character to Different Face ModelsCOMPUTER GRAPHICS FORUM, Issue 8 2008Verónica Costa Orvalho I.3.7 Computer Graphics: Three-Dimensional Graphics and Realism. Animation Abstract We introduce a facial deformation system that allows artists to define and customize a facial rig and later apply the same rig to different face models. The method uses a set of landmarks that define specific facial features and deforms the rig anthropometrically. We find the correspondence of the main attributes of a source rig, transfer them to different three-demensional (3D) face models and automatically generate a sophisticated facial rig. The method is general and can be used with any type of rig configuration. We show how the landmarks, combined with other deformation methods, can adapt different influence objects (NURBS surfaces, polygon surfaces, lattice) and skeletons from a source rig to individual face models, allowing high quality geometric or physically-based animations. We describe how it is possible to deform the source facial rig, apply the same deformation parameters to different face models and obtain unique expressions. We enable reusing of existing animation scripts and show how shapes nicely mix one with the other in different face models. We describe how our method can easily be integrated in an animation pipeline. We end with the results of tests done with major film and game companies to show the strength of our proposal. [source] The embedded ion method: A new approach to the electrostatic description of crystal lattice effects in chemical shielding calculationsCONCEPTS IN MAGNETIC RESONANCE, Issue 5 2006Dirk Stueber Abstract The nuclear magnetic shielding anisotropy of NMR active nuclei is highly sensitive to the nuclear electronic environment. Hence, measurements of the nuclear magnetic shielding anisotropy represent a powerful tool in the elucidation of molecular structure for a wide variety of materials. Quantum mechanical ab initio nuclear magnetic shielding calculations effectively complement the experimental NMR data by revealing additional structural information. The accuracy and capacity of these calculations has been improved considerably in recent years. However, the inherent problem of the limitation in the size of the systems that may be studied due to the relatively demanding computational requirements largely remains. Accordingly, ab initio shielding calculations have been performed predominantly on isolated molecules, neglecting the molecular environment. This approach is sufficient for neutral nonpolar systems, but leads to serious errors in the shielding calculations on polar and ionic systems. Conducting ab initio shielding calculations on clusters of molecules (i.e., including the nearest neighbor interactions) has improved the accuracy of the calculations in many cases. Other methods of simulating crystal lattice effects in shielding calculations that have been developed include the electrostatic representation of the crystal lattice using point charge arrays, full ab initio methods, ab initio methods under periodic boundary conditions, and hybrid ab initio/molecular dynamics methods. The embedded ion method (EIM) discussed here follows the electrostatic approach. The method mimics the intermolecular and interionic interactions experienced by a subject molecule or cluster in a given crystal in quantum mechanical shielding calculations with a large finite, periodic, and self-consistent array of point charges. The point charge arrays in the EIM are generated using the Ewald summation method and embed the molecule or ion of interest for which the ab initio shielding calculations are performed. The accuracy with which the EIM reproduces experimental nuclear magnetic shift tensor principal values, the sensitivity of the EIM to the parameters defining the point charge arrays, as well as the strengths and limitations of the EIM in comparison with other methods that include crystal lattice effects in chemical shielding calculations, are presented. © 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part A 28A: 347,368, 2006 [source] Equation of State of Strongly Coupled Quark,Gluon Plasma , Path Integral Monte Carlo ResultsCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7-8 2009V.S. Filinov Abstract A strongly coupled plasma of quark and gluon quasiparticles at temperatures from 1.1Tc to 3Tc is studied by path integral Monte Carlo simulations. This method extends previous classical nonrelativistic simulations based on a color Coulomb interaction to the quantum regime. We present the equation of state and find good agreement with lattice results. Further, pair distribution functions and color correlation functions are computed indicating strong correlations and liquid-like behavior (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dynamics of Dislocations in a 2D Plasma CrystalCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4-5 2009V. Nosenko Abstract Recent experimental results on the dislocation dynamics in a two-dimensional plasma crystal are reviewed. A single layer of micron-size microspheres was suspended in the sheath of a capacitively coupled rf discharge. The particles self-organized in a triangular lattice. Edge dislocations were created in pairs in this plasma crystal when the internal shear stress built up above a threshold, due to the crystal's slow differential rotation. Basic stages of dislocation nucleation were identified and studied, from gradual pile-up of shear strain in the crystal to eventual escape of free dislocations. After nucleation, dislocations moved supersonically with respect to the shear waves and generated shear-wave Mach cones (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Oxide layer dissolution in Si/SiOx/Si wafer bonded structuresCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2009N. Zakharov Abstract The evolution of the interfaces of hydrophilic-bonded Si wafers and the corresponding low-angle twist boundary have been analysed in relation to thermal annealing and their relative crystallographic orientation. Two orientation relationships were investigated: Si<001>/Si<001> and Si<001>/Si<110>, where the interfaces are seperated by thin native SiO2 layers. The interfaces were analysed by TEM and STEM/EELS. It is found that the decomposition rate of the intermediate oxide layer and the formation of a Si(Si bonded interface depend very much on the lattice mismatch and on the twist angle. The velocity of the dissolution of the thin oxide layers and the formation of Si(Si bonds at the bonding interface depend on the orientation relations of the corresponding wafers. The processes of interface fusion and the dissolution of oxide layer are discussed. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical and dielectric studies on pure and Ni2+, Co2+ doped single crystals of bis thiourea cadmium chlorideCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2008R. Uthrakumar Abstract Good quality single crystals of Ni2+, Co2+ ions doped Bisthiourea Cadmium Chloride (BTCC) are some of the excellent and efficient non-linear optical materials grown from aqueous solution by slow evaporation method. The lattice parameters of the grown crystals are determined by single crystal X-ray analysis. UV spectral analyses on these samples reveal the improved transparency of the doped crystals ascertaining the inclusion of metal ion in the lattice. FTIR spectral analysis carried out on the materials confirm the presence of functional groups. Dielectric measurements reveal that the dielectric constant of pure and doped crystals decreases with increase of frequency. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterisation of Zn:LiNbO3/Mg:LiNbO3 multilayer thin films grown by liquid phase epitaxyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2006H. J. Lee Abstract 1, 3 and 5 mol% ZnO doped LiNbO3 film and 2 mol% MgO doped LiNbO3 multilayer films were grown on the LiNbO3 (001) substrate by liquid phase epitaxy (LPE) method with a Li2O-V2O5 system. We examined the optical transmission spectra of the Zn:LiNbO3 by Fourier Transform-Infrared Spectrophotometer (FT-IR). The crystallinity and the lattice mismatch between the Zn:LiNbO3 film and Mg:LiNbO3 film was confirmed by x-ray rocking curve (XRC) and observed the ZnO and MgO distribution in the cross-section of the multilayer thin films by electron probe micro analyzer (EPMA). Furthermore, the surface morphology of the films was observed using atomic force microscopy (AFM). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnonic excitations versus three-dimensional structural periodicity in magnetic compositesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2006M. Krawczyk Abstract The study deals with the spin wave spectrum in magnetic macrostructure (composed of two ferromagnetic materials) showing a 3D periodicity; the structure considered consists of spherical ferromagnetic grains disposed in the nodes of a simple cubic crystal lattice and embedded in a matrix with different ferromagnetic properties. It is shown that the magnonic spectrum of this composite structure exhibits frequency regions forbidden for magnon propagation, and the energy gaps are sensitive to the exchange contrast between the constituent materials as well as to the magnetization contrast. The widths of the respective magnonic gaps are studied as functions of parameters characterizing the magnetic structure. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and characterization of potassium magnesium sulphate hexahydrate crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2006M. Dhandapani Abstract Potassium magnesium sulphate hexahydrate (picromerite) was synthesized and single crystals were obtained from saturated aqueous solution by slow evaporation method at room temperature. The crystals were bright, colourless and transparent having well defined external faces. The grown crystals were characterized through Fourier Transform Infrared (FTIR) spectral studies and thermal analysis. The FTIR data were used to assign the characteristic vibrational frequencies of the various chemical bonds in the compound. The compound crystallizes in monoclinic lattice with the space group P21/c. The thermogravimetry (TG) indicates the removal of only two water molecules around 100 °C. A suitable decomposition pattern was formulated based on the percentage weight losses observed in TG of the compound. The results of differential thermal analysis (DTA) conform to the results of TGA. Differential scanning calorimetry (DSC) analysis carried out at high temperature suggests that the occurrence of two phase transitions in the crystal between 140 and 180 °C. When the crystal was cooled below the room temperature up to ,170 °C, no thermal anomaly was observed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis, structural and thermal studies of tetrathioureacopper(I) chloride crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2005M. Dhandapani Abstract Tetrathioureacopper(I) chloride, hereafter abbreviated as TCC, was synthesised and single crystals were obtained from saturated aqueous solution by slow evaporation (solution growth) method at room temperature. The crystals obtained are bright, colourless and transparent having well defined external faces. The grown crystals were characterized through elemental analysis, single crystal X-ray diffraction study, thermal analysis, electron spin resonance spectroscopy and Fourier Transform infrared spectroscopy. The elemental analysis confirms the stoichiometry of the compound. The single crystal diffraction studies indicate that TCC crystallises in the tetragonal lattice and the unit cell parameters are a = b = 13.4082 Å, c = 13.8074 Å, V = 2482.29 Å3, , = , = , = 90°. Space group and the number of molecules per unit cell (Z) are found to be P41212 and 8 respectively. The TG curve of the sample shows a prolonged decomposition from 210 to 628.3 °C, from which the decomposition pattern has been formulated. The endothermic peaks in the DTA curve indicate melting and decomposition of the compound at 165.2 and 633.8 °C respectively. An exothermic peak in high temperature DSC indicates a phase transition in the compound at 274.8 °C. Thermal anomalies observed in the low temperature DSC at ,163.3, ,152.0, ,141.5, ,108.3, 1.0 and 12.1 °C in the heating run and ,157.1 and ,153.9 °C in the cooling run reveal first order phase transitions in the crystal. The peaks observed at ,146.2 °C in both the heating and cooling runs suggest occurrence of a second order phase transition in this compound. The IR spectroscopic data were used to assign the characteristic vibrational frequencies of various groups present in the compound. The ESR study confirms that the copper is in the +1 oxidation state in the complex. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||||||||||||||||||||||||||